The objective of this study was to make a comparison of the effects of EA betweem ipsilateral acupoints and contralateral acupoints on noci- ceptive afferent impulses of peripheral nerve

and further to analyse the mechanism of the effect of EA at acupoints on different sides. Rabbits were anesthetized with chloralose-urethan and paralyzed. The peroneal nerve was placed on two pairs of electrodes for stimulation and tecording of the compound action potentials elicited by electrical stimuli with a strength sufficient for exciting all C--fibers. Acupoints were divided into two groups: (1) "Zusanli" and "Shangjuxu"; ipsilateral to nocicepti- ve stimulation; (2) "Sanyinjiao" and "Yinlingchuan" contralateral to no- ciceptive stimulation. The changes of the amplitude of C wave were obse- rved at 5min

10min during EA and 5min

10min and 20min after ceasing EA. The results indicated that the amplitudes of C wave were significantly decreased by EA of both group acupoints (P<0.05). It suggests that EA at both "ZusanIi" "Shangjuxu" and "Sanyinjiao" "Yinlingchuan" plays a frole in resisting the nociceptive afferent impulses. After a central lesion of the sciatic nerve ipsilateral to nociceptive stimulation

there was a de- pressed trend of C potential when "Zusanli" "Sangjuxu" were stimulated by EA

but there was no similar effect of EA when "Sanyinjiao" "Yinli- ngchuan" were stimulated. It suggests that the inhibitory effect of EA ipsilaterai to nociceptive stimulation has peripheral mechanism besides ce- ntre mechanism.